Cylinder locks are widely known and used as locking mechanisms in doors, windows, boxes, cases, drawers, safes, padlocks, bicycle locks, etc. The mechanical cylinder lock has one or two cylinder-shaped plugs rotatable by an inserted key to move a locking bolt from the door into the door frame or backwards, thereby locking or unlocking the door. The mechanical varieties of cylinder locks are standardized to allow mass production and convenient replacement and retrofitting of existing doors. Examples of conventional mechanical cylinder locks such as Euro Profile cylinder lock 1, Swiss cylinder 2, and Schlage® cylinders 3 and 4 are shown in FIG. 1.
Electronic locks are also known. Some electronic locks have a keypad control panel near the door or on the door itself, which is used to input an entry code. Other types have magnetic card readers for input of the entry code, as used in hotels and some condominiums. Yet others have sophisticated receivers and may be operated remotely, for example door locks of cars. Electronic locks generally offer a higher level of security and convenience than the mechanical locks, however they need specially designed and manufactured locks, power supply and wiring. They are more expensive for installation and maintenance and more susceptible to accidental or ill-intended damage.
There are attempts to combine the advantages of the electronic locks and the mechanical locks, especially when retrofitting existing doors with new electronic locks. US Pat. Application 2001/0027671 discloses a system comprising electronic cylinders and electronic keys. The electronic cylinder has no power supply but has a built-in microprocessor and memory chip and electric contacts in a recess accepting the key bit. The electronic key contains a battery to operate the cylinder, and a microprocessor with memory. The key serves also as a handle to turn the cylinder in the lock and to open the lock bolt.
WO 99/61728 discloses an electronic cylinder lock comprising an inner and an outer cylinder plug, a battery, a servomotor, a control unit, and a mechanical clutch. The servomotor and the clutch are disposed in the cylinder between the plugs, in a rotary cam engaged with the locking bolt. An electronic key for this lock is described in WO 97/48867. The coded signal is transmitted via electric contacts in the key bit and in a recess in the cylinder plugs. Normally, neither cylinder plug is engaged to the rotary cam. When a key is inserted in one of the plugs and the coded signal is recognized, the servomotor operates the clutch and connects the plug to the rotary cam.
While each of the above constructions has its advantages, it is desirable to avoid some deficiencies such as electric contacts or any code-input devices exposed to tampering or malevolent damage, etc.
WO92/21844 and DE 4234321A1 disclose an electronic cylinder lock containing a battery, a servomotor, a control unit, and an optical guide disposed along the cylinder axis and reaching the outer surface of the cylinder (the recess for the key). A key with a battery, a microprocessor, and a light source is inserted in the recess and a coded light signal is emitted. The signal passes through the optical guide to a control unit sensor, and after identification, the servomotor releases the cylinder, which can now be rotated by the key to move the door lock bolt.
U.S. Pat. No. 6,411,195 discloses a data transmission system including a data transmitting device having a reciprocable impact head for delivering an encoded series of mechanical impacts to a first surface of an impact transmissive body such as a door, and a data receiving device having a sensitive microphone at a second surface of the impact transmissive body for picking up vibrations resulting from the series of impacts. The data transmission system is suitable for use in coded access systems.